Sttn89

i recently converted my caprice to carburator from tbi.I added a mechanical pump but i dint remove the pump out thetank,When pressure builds up the fuel comes out of the return line with alot of force splashiung gas everywhere.Am i supposed to plug the return line or is there something i have to do with the pump in the tank fuel pressure jumpms from 5 to 10 psi while the car is running when off its about 10 psi.any info is welcome

Apeiron

What pressure regulator are you using with the carb?

Sttn89

i dont have it hooked up but it is a mr gasket adjustable regulator.

Sttn89

i get pressure readings thru the dual feed line.The cardb is a 650 double pumper

Apeiron

Does the regulator have a return port?

3rdgenmaro

iTrader: (9)

Just to be clear, Are you running both the electric and the mechanical pumps? Or are you sucking through the electric with the mechanical?

IMO, ditch the Mr. Gasket, pick up a holley regulator, remove the mechanical pump, and just use the electric.

taonindo

i agree...and do so before running the car any more. the pressure can build up and blow the hose off dumping fuel in the engine compartment catching fire, next thing you know you have a corvette that needs a new fiber glass front end.....oh wait that was me.

Sttn89

The regulator doesnt have a return port on.I am just using the mech. pump but i never removed the eletric pump out of the tank.And just for the record the mr. gasket regulator IS NOT INSTALLED but i do have one.Itcame with an eletric 105 gph pump bui dont have that.the regulator has a max psi of 14 psi.Seems like a good regulator so i dont wanna get another regulator if not absolutly neccessary

Apeiron

Are you powering the stock electric pump, or no? If yes, you must have a return line in the system somewhere. If no, then the mechanical pump doesn't work too well sucking through the stalled pump in the tank.

Sttn89

To my knowledge the intank pump is not operating but i am not for sure.I hve turned the key and tried to listen but didnt hear it coming on.So being so the pump was not removed from the tank that can be causing a ristriction for the mech. pump?If so what woul be cauing the sudden surging of fuel from the return line.Is it to much pressure because i ont have the regulatr installed??Im really stumped and I wanna drive the car..

Sttn89

i have also noticed that wen i ride with the gas cap off no fuel shoots out .I know this is because of the lowered pressure but will plugging the line cause to much pressure??Are there any prssure relief gas caps or something i can use??

t-top havoc

iTrader: (3)

I would either
( 1 ) remove the tank pump & install an appropriate length of hard fuel line ( stainless steel or aluminum, using a compression fitting ) & a sock filter.
Or
( 2 ) get a Mallory regulator # 4309 IIRC, & set pressure at 5 1/2 or 6 lbs, hook up the return.

Carb pressure is WAY less than 14 lbs!!
What fuel pump is on the block? It may be a high pressure unit requiring a regulator.

( edit )

https://www.thirdgen.org/forums/carb...nk-pickup.html

After you read it, note post # 33

Hope this helps

8t2 z-chev

back when i clapped a temporary carb setup on my z28
when i had the crossfire off for modification,i also had a
pressure buildup in the gas tank-cause was the
charcoal canister valves were not working as the ECM
was inactive during this time-put a vented gas cap on
until i finished the crossfire modifications and got the
system up and running again.

Sttn89

what kind of gas cap exactly can I get for the time being

8t2 z-chev

IIRC,i used a "carb" gas cap-CFI gas cap is not vented,
but carb one was as i recall...Was back in '94 i had the
temporary carb setup on,my memory could be wrong-
best to inspect both carb and TBI caps to verify..

Apeiron

No thirdgen caps are vented, but not having an ECM doesn't impair venting of the tank in any way. Only a plug in the vent line can do that.

Sttn89

so basically you r saying that something is clogging my vent line?I wil check that out.

Apeiron

I'm saying nothing like that.